The signalling means of the present invention utilizes some of the underlying principles employed by apparatus as disclosed in my prior U.S. Pat. Nos. 3,717,845; 3,827,393 and 3,828,149. The present invention includes differences over said prior apparatus. In the present invention, the gaseous fluid under pressure released from the container is utilized to actuate visual signalling means and only so much thereof as is essential for that purpose is permitted to escape from the container. When the signalling means has been actuated to display a signal indicating a diminution of pressure, further discharge of gaseous fluid from the container is prevented, thereby retaining the gaseous fluid in the container to the greatest extent possible under the circumstances.
Basically, the apparatus of the invention is preferably used as a composite replacement for standard known tire valve structures, functionally incorporating the operational features thereof, while additionally serving as a pressure loss indicator for the tire.